Constraints on the DGP Model from Recent Supernova Observations and Baryon Acoustic Oscillations

Abstract

Although there is mounting observational evidence that the expansion of our universe is undergoing a late-time acceleration, the mechanism for this acceleration is yet unknown. In the so-called Dvali-Gabadadze-Porrati (DGP) model this phenomena is attributed to gravitational leakage into extra dimensions. In this work, we mainly focus our attention to the constraints on the model from the gold sample of type Ia supernovae (SNeIa), the first year data from the Supernova Legacy Survey (SNLS) and the baryon acoustic oscillation (BAO) peak found in the Sloan Digital Sky Survey (SDSS). At 99.73% confidence level, the combination of the three databases provides Omega_m=0.270^{+0.018}_{-0.017} and Omega_{r_c}=0.216^{+0.012}_{-0.013} (hence a spatially closed universe with Omega_k=-0.350^{+0.080}_{-0.083}), which seems to be in contradiction with the most recent WMAP results indicating a flat universe. Based on this result, we also estimated the transition redshift (at which the universe switches from deceleration to acceleration) to be 0.70 < z_{q=0} < 1.01, at 2 sigma confidence level.